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Wiper Power And Confusion.


Davo

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Hi, I'm just getting to know my newly acquired 84 sierra trimmed with a Robin Hood mk 1.

 

Today's project is getting the wiper to work properly. I don't really understand how the wiper wiring loom works, but I'll talk you through my fault finding process; but please go easy if I've made any glaring mistakes.

 

With the ignition on I can move the wiper stalk to any position or the water pump and neither works.

 

I pulled out the wiper module and put a tester on each of the terminals. As far as I can see there is no voltage on any terminal.

 

If I put a piece of wire from the battery straight to a terminal where the wiper module was the wipers start working. If I move the stalk up and down they even change speed. The washer also works.

 

This must be good news as it means the wiper motor and washer both work.

 

It also must mean that the stalk works.

 

I guess there must also be a working potentiometer in there as well to control the speed.

 

So if all functions exist without a wiper module in place, what does it even do ? Is it for intermittent wiping? A non existent rear wiper maybe? I know there is a rear wiper button on the dash but I have no idea why it's there.

 

I guess the easiest option would be to cheat and directly provide power as I did today. But that can't be right?

 

Can anyone shed any light on what might be happening please.

 

David

 

Bournemouth

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Because Kitcars have such random parts it would help if you could tell the components in yours.

Are you using sierra stalks? If so what part number. It's engraved/stamped on them. 84 sierra should have a number begining 83BGXXXXXXXX.

Next what wiper motor are you using? Usual choices are the sierra motor or the lucas motor. Both should have 5 wires to them and one of those wires in each case should be live when the ignition is live.

Depending on your builder that ignition live should be a fused live. So first check is the fuse.

 

No potentiometer. The two speeds are simply two different circuits.(Unlike heater motors where speed is varied by resistances) Intermittent if further controlled by the park circuit.

If the ignition live supply to the stalk is bust you get nothing. If you have supply to the switch but the ignition live supply to the motor is bust they work but don't park and there is no intermittent.

Not sure what 'module' you have. The sierra didn't use a module for slow/fast/park circuits. Just the stalks and motor. Yours may have had a fixed interval delay wipe relay or a variable delay wipe relay with a rheostat. Either could be fitted or none. (I would pull the plug on it for the time being while you work on the main system)

 

Nigel

 

Is Bournemouth in a different time zone?

Edited by Longboarder
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Thank you both. The fuse does appear to be i the black box. The fuse passed my continuity check.

 

So next step was to feed the upper half of the fuse terminal which would have ordinarily be fed by the bottom half with 12v. Doing that the wipers work fully inc intermittent setting.

 

So to me this means Im not getting a live to the fuse.

 

I guess I have two choices now, find the feed wire to that fuse and work out where the break is or make a new 12v feed to that fuse

 

Or maybe a third choice of using a new 12v feed but putting an inline fuse or something.

 

 

 

I can see on diagrams that the fuse gets a feed from an ignition relay. Presumably the ignition relay feeds multiple 12v lines. Im not sure what it would look like though.

 

I dont think its so relevant now but the stalk is 83bg11k665*a

 

I cant read the * unfortunately

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Even if based on the sierra diagrams it might be much modified. There may not be an ignition relay. If there is then it will have double size blades because it carries a beefy current.

If you can access the fusebox easily then running a new ignition live feed to the fuse would be good. Tracing and fixing the faulty feed to the fuse would also be good.

Taking the wiring to the wipers out of the fusebox and using a new ignition live and an inline fuse would work but is a bit scruffy.

 

However, glad you have narrowed it right down and a fix should be easy.

 

Nigel

Edited by Longboarder
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Cheers, the fuse box is very tight at the moment as the cables behind it are all cable tied. If I dare cut the cable tie and risk disturbing other problems Ill either be able to find the fault or run a new live. Thanks for the help. Ill let you know how it goes.

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